9317 ‎(2)‎

• UCREFRP Catalog Number: 9317
• Author: Spahr, N. E., L. E. Apodaca, J. R. Deacon, J. B. Bails, N. C. Bauch, C. M. Smith and N. E. Driver.
• Title: Water Quality in the Upper Colorado River Basin, Colorado, 1996-98.
• USFW Year: 2000.
• USFW - Doc Type: Denver.
• Copyright Material: NO

10
~
Z ex:
0 w
.....
~ :J
ex: ex:
..... w
Z 0..
W CIl 0.1
() ::;
Z <::
0 ex:
() "
Z :J
<:: -'
15 :i! 0.01
w
::;
0.001
Ammonia

[] Agriculture Sites . Southern Rocky Mountains
El Colorado Plateau Reference Site Urban Sites
LJ Colorado Plateau Mixed . Southern Rocky Mountains
Land-Use Sites Mixed Land,Use Sites
~ Median below 0.01 mg/L

Nitrite Plus
Nitrate

Total RlOSphorus

Dissolved Orthophosphate
Phosphorus

NUTRIENT

Figure 14. Concentrations of nutrients in agricultural areas of the UCOL were
greater than concentrations in other land-use settings. A log scale is used due to
the large range of concentrations.

tive of natural conditions but is
probably representative of small
streams in the Colorado Plateau.
Median concentrations of nutrients
at agricultural sites also were

greater than median concentrations
at mixed land-use and urban sites
within the Southern Rocky Moun-
tains. The urban areas shown in the
bar chart are downstream from Vail

and Crested Butte, Colorado (fig.
6), and are streams that are not
dominated by wastewater effluent
such as might be found in large
metropolitan areas. Concentrations
of nitrite and nitrate were within
State standards for agricultural
water use. Water from the agricul-
tural streams is not commonly used
for domestic supply.
Geology and agriculture con-
tribute to elevated suspended-
sediment concentrations in the
Colorado Plateau. Suspended-
sediment concentrations in the
streams and rivers of the Colorado
Plateau were much greater than
concentrations in the Southern
Rocky Mountains (fig. 15), due in
large part to differences between
the sedimentary geology of the

Total nitrogen (the sum of nitrite, nitrate, ammonia, and organic nitrogen) concentrations at the VCOL agricul-
tural monitoring sites (Reed Wash and Dry Creek) were ranked in the group of national agricultural sites with the
highest concentrations. The map below shows a comparison of average annual total nitrogen concentrations at the
two VCOL agricultural sites with agricultural sites in other NAWQA Study Units. The average concentrations for
the VCOL sites were 3.8 milligrams per liter for Reed Wash and 3.2 milligrams per liter for Dry Creek and are
less than State instream standards. Average annual total phosphorus concentrations at the two agricultural sites in
the VCOL also ranked among the group of national agricultural sites with the highest total phosphorus concentra-
tions.

TOTAL NITROGEN IN STREAMS-AGRICULTURAL AREAS

A<Jl---i--... {"
EXPLANATION . t~/ ~I \ ----_~..,~. '~ \
T.! ,,-,!Y.:::( , l,.r;.YrQJ , "'-'-,"" '1
Average annual concentration of total nitrogen, If} j ~ I - \. ~~-'-.1.' ~,__ Y
in milligrams per liter ~ ~r---....._F-- . ( ~ :('\ (If
~ <' -' .. 1
· Highest (greater than 2.9) ~. _. _ i L-_~_J.' .2. \ ~. .___"'\. ~
. Medium (0.64 to 2.9) \ L ~ ~ ";-- .j~~ ,-"
@ Lowest (less than 0.64) ,.~- ' r. r-- l?~_ eIl~\.-i1' ~\)
.~ \ r" V w~Jif~)
." I fr;'~ Co-.d"~
o,j-' f .o' -.~-
Average annual total nitrogen input, l" \I ~F~ -~ ..~ , -~" )
in pounds per acre, by county, for 1995-98. ,\? I J ;> ~ '
Inputs are from fertilizer, manure, and the atmosphere "-J. ...J .'--~'---~1'. _.1.1..... '\

D Greater than 25 pounds per acre Reed Wash ~ .. .~, L~_ \ .__
o 6 to 25 pounds per acre 0 C k\' =~.' I ~jr
ry ree . ',,, .._."......"
o Less than 6 pounds per acre 1 .-

~

18 Water Quality in the Vpper Colorado River Basin